FIG. 2.

Results of each step in the fabrication of freestanding 3-D tubular networks in alginate hydrogel. The four images represent the four steps of the fabrication process. A thin, transparent layer of alginate gel coated the copper scaffold after electrolysis in alginate solution (a), the tubular networks turned light blue (b) after further electrolysis in CaCl₂. Then the tubular networks became yellow (owing to iron (III) ions) after the remaining Cu pieces dissolved in FeCl₃ (c). In the last step, the color of the tubules returned to light white after the Fe³⁺ ions were replaced with Ca²⁺ ions in a mixture solution of CaCl₂ and EDTA acidic solution (d). Inset shows freestanding 3D microvascular networks. The scale bars are 10 mm long.